//  DominanceComparator.java
//
//  Author:
//       Antonio J. Nebro <antonio@lcc.uma.es>
//       Juan J. Durillo <durillo@lcc.uma.es>
//
//  Copyright (c) 2011 Antonio J. Nebro, Juan J. Durillo
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU Lesser General Public License for more details.
// 
//  You should have received a copy of the GNU Lesser General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.

package jmetal.util.comparators;


import hidra.jmetal.core.Solution;

import java.util.Comparator;


/**
 * This class implements a <code>Comparator</code> (a method for comparing
 * <code>Solution</code> objects) based on a constraint violation test + 
 * dominance checking, as in NSGA-II.
 */
public class DominanceComparator implements Comparator{
 
	
	
	
	
	
	
	/** 
	   * stores a comparator for check the OverallConstraintComparator
	   */
	  private static final Comparator overallConstraintViolationComparator_ =
	                              new OverallConstraintViolationComparator();
	 
	  
	  //static double EPS = 0.001;
	  
	  /**
	  * Compares two solutions.
	  * @param object1 Object representing the first <code>Solution</code>.
	  * @param object2 Object representing the second <code>Solution</code>.
	  * @return -1, or 0, or 1 if solution1 dominates solution2, both are 
	  * non-dominated, or solution1  is dominated by solution22, respectively.
	  */
	  public int compare(Object object1, Object object2) {
	    if (object1==null)
	      return 1;
	    else if (object2 == null)
	      return -1;
	    
	    Solution solution1 = (Solution)object1;
	    Solution solution2 = (Solution)object2;

	    int dominate1 ; // dominate1 indicates if some objective of solution1 
	                    // dominates the same objective in solution2. dominate2
	    int dominate2 ; // is the complementary of dominate1.

	    dominate1 = 0 ; 
	    dominate2 = 0 ;
	    
	    int flag; //stores the result of the comparison

	    if (solution1.getOverallConstraintViolation()!= 
	        solution2.getOverallConstraintViolation() &&
	       (solution1.getOverallConstraintViolation() < 0) ||         
	       (solution2.getOverallConstraintViolation() < 0)){            
	      return (overallConstraintViolationComparator_.compare(solution1,solution2));
	    }
	                                                
	    // Equal number of violated constraints. Applying a dominance Test then
	    double value1, value2;
	    for (int i = 0; i < solution1.numberOfObjectives(); i++) {
	      value1 = solution1.getObjective(i);
	      value2 = solution2.getObjective(i);
	      if (value1  < value2) {
	        flag = -1;
	      } else if (value1  > value2) {
	        flag = 1;
	      } else {
	        flag = 0;
	      }
	      
	      if (flag == -1) {
	        dominate1 = 1;
	      }
	      
	      if (flag == 1) {
	        dominate2 = 1;           
	      }
	    }
	            
	    if (dominate1 == dominate2) {            
	      return 0; //No one dominate the other
	    }
	    if (dominate1 == 1) {
	      return -1; // solution1 dominate
	    }
	    return 1;    // solution2 dominate   
	  } // compare
	  
	  
	
	
	
	
	
	
	
	
	
	
	
	
  /** 
   * stores a comparator for check the OverallConstraintComparator
   *//*
  private static final Comparator overallConstraintViolationComparator_ =
                              new OverallConstraintViolationComparator();
 *//**
  * Compares two solutions.
  * @param object1 Object representing the first <code>Solution</code>.
  * @param object2 Object representing the second <code>Solution</code>.
  * @return -1, or 0, or 1 if solution1 dominates solution2, both are 
  * non-dominated, or solution1  is dominated by solution22, respectively.
  *//*
  public int compare(Object object1, Object object2) {
    if (object1==null)
      return 1;
    else if (object2 == null)
      return -1;
    
    Solution solution1 = (Solution)object1;
    Solution solution2 = (Solution)object2;

    int dominate1 ; // dominate1 indicates if some objective of solution1 
                    // dominates the same objective in solution2. dominate2
    int dominate2 ; // is the complementary of dominate1.

    dominate1 = 0 ; 
    dominate2 = 0 ;
    
    int flag; //stores the result of the comparison

    if (solution1.getOverallConstraintViolation()!= 
        solution2.getOverallConstraintViolation() &&
       (solution1.getOverallConstraintViolation() < 0) ||         
       (solution2.getOverallConstraintViolation() < 0)){            
      return (overallConstraintViolationComparator_.compare(solution1,solution2));
    }
                                                
    // Equal number of violated constraints. Applying a dominance Test then
    double value1, value2;
    for (int i = 0; i < solution1.numberOfObjectives(); i++) {
      value1 = solution1.getObjective(i);
      value2 = solution2.getObjective(i);
      if (value1 < value2) {
        flag = -1;
      } else if (value1 > value2) {
        flag = 1;
      } else {
        flag = 0;
      }
      
      if (flag == -1) {
        dominate1 = 1;
      }
      
      if (flag == 1) {
        dominate2 = 1;           
      }
    }
            
    if (dominate1 == dominate2) {            
      return 0; //No one dominate the other
    }
    if (dominate1 == 1) {
      return -1; // solution1 dominate
    }
    return 1;    // solution2 dominate   
  } // compare
  
  */
  
} // DominanceComparator
